Perforating tandem sub with thermoplastic core and body and encapsulated pin

ABSTRACT

A hybrid sub for perforating guns includes a metallic tubular body. A metallic pin member is encapsulated by a plastic body. The plastic body preferably has threads on exterior surface thereof which form a thread union with threads on the interior surface of the metallic tubular body. The pin member may be threadedly received in the interior plastic body. A perforating gun sub having a pin member encapsulated by a plastic body is also disclosed, wherein the need for an outer metallic tubular body is eliminated.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from U.S. Application Ser. No. 63/058,620, filed Jul. 30, 2020, presently pending.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT

Not applicable.

REFERENCE TO AN APPENDIX SUBMITTED ON COMPACT DISC

Not applicable.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to the field of perforating guns. More particularly, the present invention relates to subs for connecting perforating gun sections. Even more particularly, the present invention relates to a perforating gun sub consisting fully or partially of thermoplastic material.

2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98

Due to the loads and temperatures, components for use inside oil wells are often fully formed of metallic material. For example, subs which connect perforating gun sections are often formed of a metallic material. These components are produced using a material removal manufacturing process, such as machining. For example, the perforating gun sub may be machined out of a solid bar of metallic material.

Perforating guns are utilized to position and detonate a series of shaped charges so as to perforate a casing within the wellbore. Perforation of the casing and surrounding cement allows fluids to be produced and brought to the surface.

FIG. 1A illustrates a conventional perforating (perf) gun assembly 10. In FIG. 1A, it can be seen how there are plurality of perforating gun sections 12, 14, 16 and 18, wherein the perforating gun section 18 is closest to the surface. The perforating gun assembly 10 is positioned within the casing in a formation 22. While the perforating gun assembly 10 is shown vertically positioned, it is common for such an assembly to be positioned along horizontally drilled wellbores.

Positioned between the perforating gun sections 12, 14, 16 and 18 are perforating gun subs 20. The perforating gun subs 20 are used to connect the perforating gun sections and to conduct electricity and signals required to detonate the charges at the bottom of the perforating gun assembly 10.

The deepest perforating gun section 12 is the first to be detonated during the detonation process. As such, another object of the perforating gun sub is to maintain pressure within the perforating gun assembly 10 after detonation of the first perforating gun section 12 and so on.

Various patents have issued in the past relating to perforating guns. For example, U.S. Pat. No. 6,851,471, which issued to Barlow et al. on Feb. 8, 2005 discloses a perforating gun. Specifically, this patent discloses a perforating gun assembly wherein the gun is assembled in a carrier made from straight walled tubing as a primary structural member with complementary male and female threads cut into opposite ends so that gun assemblies maybe directly connected together. The male coupling includes a reinforcing sleeve threaded into an internal thread. An alignment pin is positioned in the carrier extending through the reinforcing ring and into the interior of the carrier. A charge assembly includes a charge holder tube with upper and lower alignment fixtures. The lower alignment fixture includes an alignment slot for mating with the alignment pin and a shoulder for supporting the charge assembly on the sleeve. The upper alignment fixture has an alignment pin for mating with an alignment slot in the carrier. A retainer ring may be threaded into the upper female threads to prevent removal of the charge assembly from the carrier.

U.S. Pat. No. 8,807,003, which issued on Aug. 19, 2014, to Le et al. discloses another perforating gun assembly and method. The method disclosed in the patent includes providing a gun string assembly within a wellbore and perforating the wellbore using the gun string assembly. The gun string assembly comprises a plurality of perforating guns coupled in series. A first perforating gun of the plurality of perforating guns comprises a first portion of shaped charges, and a second perforating gun of the plurality of perforating guns comprises a second portion of shaped charges operably associated with a secondary pressure generator. The first perforating gun and the second perforating gun are configured in the gun string assembly to provide a pressure transient comprising one or more pressures at a location in the wellbore that meet one or more thresholds.

Referring to FIG. 1, there is shown a perforating gun sub 20 in accordance with the prior art. The perforating gun sub 20 has a metallic body 24 with a series of male threads 26 on each side thereof. The typical perforating gun sub 20 is a male-male pin connector. A pin member 28 extends through the interior of the metallic body 24. The pin member 28 is constructed of a conductive material such as aluminum or steel so as to pass current and/or signals through the perforating gun assembly to reach the furthest perforating gun section. As it is necessary to insulate the metallic body 24 from the pin 28, a Polyether Ether Ketone (PEEK) encapsulation 30 is provided over the pin member 28. The PEEK encapsulation 30 represents a significant cost in the traditional perforating gun sub.

A nut 32 is utilized to hold the pin member 28 into place within the metallic body 24 of the perf gun sub. Several O-rings 40 may be utilized as well.

Also shown in FIG. 1 are recesses 38 at each end of the perforating gun sub 20. The first end 34 of the perforating gun sub 20 is connectable to the bottom of an upper perforating gun section, while the second end 36 is connectable to the top of a lower perforating gun section. Specifically, the male threads 26 adjacent the first end 34 of the perforating gun sub 20 would engage with female threads of an upper perf gun section, while the male threads 26 adjacent the second end 36 of the perf gun sub would engage with the female threads of a lower perf gun to the section.

The conventional perforating gun sub is made utilizing a material removal manufacturing process, such as machining As such, the perforating gun sub 20 as shown in FIG. 1 is produced starting with a solid bar or cylinder of metallic material, and then the interior passageways and recesses are machined out. It is obvious that this process becomes costly for high-volume manufacturing runs such as those used in perforating gun parts manufacturing.

Various patents have issued in the past relating to connection systems and subs for perforating guns. For example, U.S. Pat. No. 7,210,524, which issued on May 1, 2007, to Sloan et al. discloses a perforating gun quick connection system. In particular, the patent discloses a connection system to be used in conjunction with a perforating gun comprising a top sub formed to receive one end of a gun body of a perforating gun, a circumferential groove disposed on the outer surface of the gun body, and a collet secured to the top sub. The collet has at least one finger that engages the groove. Engaging the groove with the at least one finger of the collect connects the gun body to the top sub. A cover sleeve is included that retains the finger in connective engagement with the groove.

U.S. Pat. No. 9,157,718, which issued on Oct. 13, 2015, to Ross discloses an interruption sub for perforating guns. The interruption sub includes a barrier movable between a biased closed position and an open position. The interruption sub prevents ballistic transfer to the downhole tool in the closed position and allowing ballistic transfer to the downhole tool in the open position. A detonation path within the interruption sub has a barrier which is hydraulically or electronically movable from the closed position to the open position in response to at least one condition acceptable for ballistic transfer. Also disclosed is a downhole tool activatable by detonation.

In any case, conventional perforating gun subs of the prior art present significant costs associated with manufacturing and processing.

It is an object of the present invention to provide a perforating gun sub which utilizes injection molded parts.

It is another object of the present invention to provide a perforating gun sub which is manufactured utilizing tubular parts as opposed to solid cylindrical parts.

It is another object of the present invention to provide a perforating gun sub that which significantly reduces or completely eliminates manufacturing costs associated with removal of the metallic material from a bar or cylinder.

It is another object of the present invention to reduce the number of parts associated with the perforating gun sub.

It is another object of the present invention to provide a perforating gun sub which maintains pressure within the perforating gun string.

It is another object of the present invention to provide a perforating gun sub which reduces material costs for manufacturing of the perforating gun sub.

It is another object of the present invention to reduce the weight of the perforating gun sub.

It is yet another object of the present invention to provide a perforating gun sub which eliminates the need for expensive PEEK components.

In an embodiment, it is an object of the present invention to provide a perforating gun sub which entirely eliminates the need for metallic exterior components.

These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.

BRIEF SUMMARY OF THE INVENTION

The present invention is a sub for perforating guns including a metallic tubular body having interior with female threads on the surface thereof, a plastic body having male threads on the exterior surface thereof. The plastic body is threadedly received in the interior of the metallic tubular body. A metallic pin member extends through the interior of the metallic tubular body. The metallic pin member is encapsulated by the plastic body.

In an embodiment, the plastic body is not composed of a Polyether Ether Ketone (PEEK) material.

In an embodiment, the pin member has a central section and outwardly extending end sections. The central section has a maximum diameter greater than diameters of the outwardly extending and sections. In an embodiment, the central section of the pin member includes a plurality of grooves.

In an embodiment, the perforating gun sub further includes a plurality of O-rings positioned between the plastic body and the metallic body.

In an embodiment, the pin of the sub for perforating guns is a conductive material.

In an embodiment, the metallic tubular body has a ledge at one end thereof, and the plastic body has a flanged configured to abut the ledge of the metallic tubular body.

In an embodiment, the pin member is partially encapsulated, and sections of the pin member are exposed so as to connect to adjacent perforating gun sections.

In an embodiment, the pin member has male threads on an exterior surface thereof, while the plastic body has female threads on the interior surface thereof. The pin member is threadedly received the interior of the plastic body. In an embodiment, the pin member has at least one groove on the exterior surface thereof. At least one o-ring is received by the at least one groove of the pin member.

The present invention is also a sub for perforating guns including a plastic body having male threads on an exterior surface thereof, and a metallic pin member extending through an interior of the plastic body. The pin member is encapsulated by the plastic body.

In an embodiment, the pin member has a central section and outwardly extending end sections. The central section has a maximum diameter greater than diameters of the outwardly extending end sections. The pin can also be of uniform diameter, with or without grooves and still perform the job.

In an embodiment, the central section of the pin member includes a plurality of steps.

In an embodiment, the plastic body is not composed of a Polyether Ether Ketone (PEEK) material.

In an embodiment, the pin member is a conductive material.

The present invention is also a sub for perforating guns including a metallic tubular body having an interior with female threads on a surface thereof, and a plastic body having male threads on exterior surface thereof. The plastic body is threadedly received in the interior of the metallic tubular body. A metallic pin member extends for the interior of the metallic tubular body and is encapsulated by the plastic body. The pin member has male threads on an exterior surface thereof. The plastic body has female threads on interior surface thereof. The pin member is threadedly received an interior of the plastic body.

In an embodiment, the pin member has at least one groove on the exterior surface thereof. At least one o-ring is received by the at least one groove of the pin member.

In an embodiment, the plastic body has a ledge at one end thereof and the pin member has a flanged configured to abut the ledge of the plastic body.

In an embodiment, the plastic body is not composed of a Polyether Ether Ketone (PEEK) material.

This foregoing Section is intended to describe, with particularity, the preferred embodiments of the present invention. It is understood that modifications to these preferred embodiments can be made within the scope of the present claims. As such, this Section should not to be construed, in any way, as limiting of the broad scope of the present invention. The present invention should only be limited by the following claims and their legal equivalents.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a perforating gun sub of the prior art.

FIG. 1A illustrates a perforating gun assembly positioned in a formation.

FIG. 2 is a cross-sectional view of the perforating gun sub of the preferred embodiment of the present invention.

FIG. 3 is a cross-sectional view of an alternate embodiment of the perforating gun sub of the present invention, wherein the perforating gun sub lacks an exterior metallic body.

FIG. 4 is a cross-sectional view of a perforating gun sub of an alternative embodiment of the present invention, wherein the pin is threadedly received by the plastic body.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 2, there is shown the perforating gun sub 50 of the preferred embodiment of the present invention. The perforating gun sub 50 is a tandem sub. FIG. 2 illustrates a cross-sectional view of the cylindrical body of the perforating gun sub 50. The perforating gun sub 50 of the present invention preferably includes a metallic body 52. A plurality of male threads 54 are provided on the exterior of the metallic body 52 so as to connect to adjacent perforating gun sections.

A metallic pin member 56 is illustrated has extending through the interior of the perforating gun sub 50. The pin member 56 is a conductive material is encapsulated by an interior plastic body 58. The interior plastic body 58 is preferably a thermoplastic material with insulating properties, such as a nylon thermoplastic material with glass fill. By utilizing the thermoplastic interior plastic body, the need for expensive PEEK components to encapsulate the pin is eliminated.

A thread union between the interior plastic body 58 and the metallic body 52 comprises male threads 60 on the exterior of the interior plastic body 58, and female threads 62 on interior of the metallic body 52. As such, the pin member 56 and interior plastic body 58 comprise a single part which is threadedly received by the metallic body 52. A plurality of O-rings 64 may be positioned at the thread union between the interior plastic body 58 and the metallic body 52.

A first end 66 of the perforating gun sub 50 connects to the top of a lower perforating section, while the second end 68 of the perforating gun sub 50 connects to the bottom of an adjacent upper perforating gun section. At the first end 66, the metallic body 52 preferably includes a ledge 67 formed therein. The corresponding flange 69 of the interior plastic body 58 is configured to abut the ledge 67. The recess 70 is shown in the second end 68, while a V-shaped recess 72 is shown in the first end 66.

Importantly, FIG. 2 also illustrates how the pin member 56 has a central section 74 having a greater diameter than outwardly extending end sections 75 of the pin member 56. This central section 74 helps retain the pin member 56 within the interior plastic body, so as to ensure that the perforating gun sub 50 maintains pressure within the perforating gun assembly. However, a pin with uniform diameter is also within the concept of the present invention and could also perform under pressure. Preferably, the central section 74 has a plurality of grooves 76 formed therein. These steps 76 further enhance the ability of the pin member 56 to be retained within the interior plastic body 58.

FIG. 2 also illustrates how the metallic body 52 has a maximum thickness T. This maximum thickness T is much thinner than that of a conventional perforating gun sub formed from solid bar. For example, the maximum thickness T of the perforating gun sub 50 of the present invention is approximately 50% of the maximum thickness of the conventional perforating gun sub shown in FIG. 1. This represents a significant reduction in mass of the perforating gun sub 50, making it both easier to handle and less expensive to ship and machine due to shorter processing times. The perforating gun sub 50 of the present invention has the required strength to be used in perforating gun assemblies, while also being of a significantly reduced weight and cost.

Referring to FIG. 3, there is shown an alternative embodiment of the present invention. In FIG. 3, there is shown a cross-sectional view of the cylindrical-shaped perforating gun sub 80. In this embodiment, the perforating gun sub 80 completely eliminates the need for an outer metallic body and thus machining, by making the sub almost entirely of injection molded thermoplastic. The perforating gun sub 80 has an entirely plastic body 82. Male threads 84 are shown on the exterior surface thereof These male threads 84 are generally longer than the threads in the metallic body example of FIG. 2. This increased length of the perforating gun sub 80 is provided to compensate for the loss of strength associated with elimination of the metallic body.

The metallic pin member 86 is shown as being encapsulated within the plastic body 82. The pin member 86 extends between the first end 88 and the second end 90 of the perforating gun sub 80. Recesses 92 and 94 are shown on the second end 90 and first end 88, respectively.

As with the embodiment shown in FIG. 2, the perforating gun sub 80 of the alternative embodiment of the present invention preferably has a section of greater diameter 96 as compared to the outwardly extending end sections of the pin member 86. A plurality of steps 98 are preferably formed in the section of greater diameter 96 of the pin member 86.

The perforating gun sub 80 of the alternative embodiment of the present invention entirely eliminates the need for an outer metallic body, thus saving significantly on costs associated with manufacturing the perforating gun and also cost associated with the shipping of the perforating gun sub.

FIG. 4 illustrates another alternative embodiment of the present invention. In this alternative embodiment, the perforating gun sub 100 includes an exterior metallic body 102 with male threads 104 on an exterior surface thereof A metallic pin member 106 is encapsulated by an interior plastic body 108. However, in the alternative embodiment of FIG. 4, the pin member 106 has a threaded section 122 with male threads engaging with corresponding female threads on the interior plastic body 108. Preferably, this threaded section 122 has a greater diameter than the remaining sections of the pin member 106.

As with the case in FIG. 2, the embodiment shown in FIG. 4 has male threads 110 on the exterior surface of the interior plastic body 108, which form a thread union with female threads 112 on the interior surface of the metallic body 102. A plurality of 0-rings 114 are also utilized at the thread union between the metallic body 102 and the interior plastic body 108.

The pin member 106 of the alternative embodiment of the present invention may also have a plurality of grooves 124 formed thereon to house O-rings 125.

FIG. 4 also illustrates how the perforating gun sub 100 has a maximum thickness T which is significantly less than the maximum thickness of the conventional perf gun sub as illustrated in FIG. 1.

FIG. 4 illustrates a series of ledges and corresponding flanges which may be formed on the metallic body 102 and the interior plastic body 108. For example, such ledges are shown the positioned at the O-rings 114 and also at the rightmost side of the perforating gun sub 100.

The perforating gun subs of the various embodiments of the present invention can be manufactured partially or fully utilizing injection molded parts, which results in significant savings in the manufacturing of the perforating gun subs. In the cases where metallic bodies are utilized, the perforating gun sub of the present invention allows for the use of tubular parts to form the metallic bodies as opposed to solid cylindrical parts or bars, which decreases machining costs associated with the removal of metallic material from the solid bar.

A reduction in the total number parts associated with the perforating gun sub also reduces the complexity of the sub and makes it easier to assemble.

In certain embodiments, the pin can be completely over molded, whereas in other embodiments it is merely encapsulated and inserted within the plastic body.

The foregoing disclosure and description of the invention is illustrative and explanatory thereof. Various changes in the details of the illustrated construction can be made within the scope of the appended claims without departing from the true spirit of the invention. The present invention should only be limited by the following claims and their legal equivalents. 

We claim:
 1. A sub for perforating guns comprising: a metallic tubular body having an interior with female threads on a surface thereof; a plastic body having male threads on an exterior surface thereof; said plastic body being threadedly received in the interior of said metallic tubular body; and a metallic pin member extending through the interior of said metallic tubular body, said pin member being encapsulated by said plastic body.
 2. The sub for perforating guns of claim 1, wherein said plastic body is not composed of a Polyether Ether Ketone (PEEK) material.
 3. The sub for perforating guns of claim 1, said pin member having a central section and outwardly-extending end sections, said central section having a maximum diameter greater than diameters of said outwardly-extending end sections.
 4. The sub for perforating guns of claim 3, said central section of said metallic pin member comprises a plurality of grooves .
 5. The sub for perforating guns of claim 1, further comprising a plurality of o-rings positioned between said plastic body and said metallic tubular body.
 6. The sub for perforating guns of claim 1, said metallic pin member being a conductive material.
 7. The sub for perforating guns of claim 1, said metallic tubular body having a ledge at one end thereof, said plastic body having a flange configured to abut said ledge of said metallic tubular body.
 8. The sub for perforating guns of claim 1, said metallic pin member being partially encapsulated, wherein end sections of said metallic pin member are exposed so as to connect to adjacent perforating gun sections.
 9. The sub for perforating guns of claim 1, said pin member having male threads on an exterior surface thereof, said plastic body having female threads on an interior surface thereof, said metallic pin member being threadedly received in an interior of said plastic body.
 10. The sub for perforating guns of claim 9, wherein said pin member has at least one groove on the exterior surface thereof, and wherein at least one o-ring is received by said at least one groove of said pin member.
 11. The sub for perforating guns of claim 1, said plastic body being composed of a nylon thermoplastic material with glass fill.
 12. A sub for perforating guns comprising: a plastic body having male threads on an exterior surface thereof; and a metallic pin member extending through an interior of said plastic body, said pin member being encapsulated by said plastic body.,
 13. The sub for perforating guns of claim 12, said pin member having a central section and outwardly extending end sections, said central section having a maximum diameter greater than diameters of said outwardly extending end sections
 14. The sub for perforating guns of claim 13, said central section of said pin member comprising a plurality of grooves.
 15. The sub for perforating guns of claim 12, wherein said plastic body is not composed of a Polyether Ether Ketone (PEEK) material.
 16. The sub for perforating guns of claim 12, said pin member being a conductive material.
 17. A sub for perforating guns comprising: a metallic tubular body having an interior with female threads on a surface thereof; a plastic body having male threads on an exterior surface thereof; said plastic body being threadedly received in the interior of said metallic tubular body; and a metallic pin member extending through the interior of said metallic tubular body, said pin member being encapsulated by said plastic body, said pin member having male threads on an exterior surface thereof, said plastic body having female threads on an interior surface thereof, said pin member being threadedly received in an interior of said plastic body.
 18. The sub for perforating guns of claim 17, said pin member having at least one groove on said exterior surface thereof, wherein at least one o-ring is positioned in said at least one groove.
 19. The sub for perforating guns of claim 17, said plastic body having a ledge at one end thereof, said pin member having a flange configured to abut said ledge of said plastic body.
 20. The sub for perforating guns of claim 17, wherein said plastic body is not composed of a Polyether Ether Ketone (PEEK) material. 